MC68HC908GZ8 FREESCALE [Freescale Semiconductor, Inc], MC68HC908GZ8 Datasheet - Page 282

• Manufacturer Part Number: MC68HC908GZ8
• Description: M68HC08 Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Development Support
The monitor ROM firmware echoes each received byte back to the PTA0 pin for error checking. An 11-bit
delay at the end of each command allows the host to send a break character to cancel the command. A
delay of two bit times occurs before each echo and before READ, IREAD, or READSP data is returned.
The data returned by a read command appears after the echo of the last byte of the command.
A brief description of each monitor mode command is given in
282
Data Returned
3
Wait one bit time after each echo before sending the next byte.
FROM HOST
SENT TO MONITOR
ECHO
Notes:
ECHO
Notes:
4
Description
ECHO
1 = Echo delay, approximately 2 bit times
WRITE
2 = Cancel command delay, 11 bit times
3 = Wait 1 bit time before sending next byte.
FROM HOST
1 = Echo delay, approximately 2 bit times
2 = Data return delay, approximately 2 bit times
3 = Cancel command delay, 11 bit times
4 = Wait 1 bit time before sending next byte.
Operand
READ
Opcode
READ
1
1
WRITE
READ
READ
MC68HC908GZ16 • MC68HC908GZ8 Data Sheet, Rev. 4
Table 20-3. READ (Read Memory) Command
Read byte from memory
2-byte address in high-byte:low-byte order
Returns contents of specified address
$4A
3
ADDRESS
4
HIGH
ADDRESS
Figure 20-13. Read Transaction
Figure 20-14. Write Transaction
Address
HIGH
High
1
ADDRESS
1
HIGH
ADDRESS
Command Sequence
Address
HIGH
High
3
ADDRESS
NOTE
4
LOW
ADDRESS
Address
LOW
Low
1
ADDRESS
1
LOW
ADDRESS
Address
LOW
Low
Table 20-3
3
DATA
3, 2
1
through
DATA
DATA
Data
Table
RETURN
4
RETURN
Freescale Semiconductor
2, 3
20-8.